Learning Anatomy
by Tohdoh
Summary: High school heartthrob Jack Frost might just become high school dropout if he didn't pass biology. Elsa, the beautiful but shy valedictorian, becomes his reluctant tutor. Soon there's bound to be more "biology" going on beyond the textbook. [Oneshot. High school AU. Jelsa sexy time.]


**Cover by stronGyu on Tumblr.**

**Warning: There be language and first time sexy time.**

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******Learning Anatomy**

'I shouldn't have signed up for Honors Biology.'

Jack knuckled his messy white hair, staring miserably at the abysmal grade stamped in angry red ink on his test.

He lost count of how many times he called himself idiot in his head. Middle of the semester, and he flunked two tests already. He was bound for failure. He only signed up for honors to please his mother, but now she'd be in for disappointment. He could only use ice hockey as an excuse so many times.

'I need to get my shit together fast,' he thought as he heaved a sigh of frustration.

Jack was itching to take off as soon as the bell rang. Mr. Bunnymund's call stopped him.

"Jack, you need to stay. Elsa, you too."

At the front row of the class, Elsa had taken her time carefully stowing away her books. As soon as she heard her name she stiffened and jerked her head up. Jack didn't need to see how genuinely confused she must look. She was the valedictorian, the top student. Ranked number one in her whole class. She likely had never been called to see a teacher after class, which wasn't often a good thing.

Jack could see her hands trembling as they tightened to fists on her desk. 'Poor thing. She must think she's in trouble. I'm pretty sure she isn't."

Students streamed out of the classroom until Jack and Elsa were the only ones left to talk to Mr. Bunnymund. The two seniors walked up to his desk and waited with silent apprehension. The Aussie-born-and-raised biology teacher eyed Jack with an unusually serious gaze.

"Jack...I hate to break it to you, kid...but you're failing my class."

Jack looked both resigned and sheepish. "I guessed as much, Mr. Bunny."

The teacher sighed. "You gotta get your act together soon. I like you because you're a nice kid, but slackin' off's coming back to bite you hard. No worries mate, it's not the end of the world. Two more tests and a final are coming up. Elsa here will be your tutor."

"E-excuse me, sir?" she stammered. She asked in surprise, not out of rudeness.

"Jack could take a few pointers from your excellent study habits," Mr. Bunnymund said. "Make arrangements to meet after school so you can share notes, or answer Jack's questions if he has any. I hope I'm not asking too much of you, Elsa."

She stiffened and gripped her backpack closer to her chest. Jack could see the reluctance in her wide blue eyes, but she probably couldn't find it in her heart to refuse the teacher. Elsa glanced at Jack for a split second, then looked away just as quickly. She finally replied with quiet compliance: "I...I'll do my best."

Jack fought to hide a gleeful smile. The thought of personally interacting with the beautiful top student made his heart flutter.

Mr. Bunnymund leaned back in his chair. "It's settled, then. Sorry for keeping you two from North's class."

From that day forward, Jack met with Elsa in the biology classroom after school. She seemed to try limiting conversation as much as possible; she'd pass him her notebook and make him copy her neat and meticulously organized notes as they sat in awkward silence. He tried to replicate every detail, even the way she made bullet point lists and highlighted key terms. He was starting to think that Elsa's brain was like a sponge, somehow being able to absorb and retain a shitload of information. More than once, he'd catch her looking at him when he glanced up from his notes.

Elsa would quickly avert her gaze and pull out her smart phone, in an attempt to put a barrier between her and Jack. She focused her eyes on the small screen, scrolling aimlessly through her Tumblr dashboard (Anna finally coerced her into getting an account just last week). Biology class at this time just _had_ to cover human reproduction, of all things.

'Why couldn't it be animal development or cellular processes?' she thought with frustration. 'That wouldn't have been so bad. Do I really have to help Jack over this section?'

She knitted her brow, flustered and feeling a blush creep up her face despite herself. Here she was, alone in a room with the hottest and most popular guy on campus. Alone. Just her. If they knew, other girls would fly into outraged hysterics and go green with envy (except for Anna, taken and perfectly happy with dating Kristoff).

Jack stared off as his pen mindlessly worked away to write, but unable to focus. Elsa was a mystery. She distanced herself from everyone else in school on two levels: academically she left others far behind to bite the dust, and socially she had neither time or desire to mingle. Top grades called for the sacrifice of social life, Jack reckoned. The only person he had seen her talk to was her sister Anna; even then, Elsa kept her distance. She never interacted much with her sister's circle of friends, preferring to keep to herself with an open book in hand or schoolwork to finish.

Jack didn't know what frustrated him more: failing to understand Elsa, or failing to understand the book in front of him.

"Damn it."

He didn't shout, but in the silence it nearly startled her. Jack scowled at the open book, with all its complicated diagrams and labels. "There's just too much information. I'm gonna need a good way to remember this." He shot her a sly glance. "How about you quiz me?"

Elsa looked visibly uncomfortable. "Y-you're sure you can't study on your own?" she stammered.

"I really need your help. Just handing me your notes isn't gonna cut it. I can't tell if I actually know the stuff or not unless you ask me the questions. Pretty please, Elsa?" For added effect, he pinned her with a smoldering pout.

Jack was impressed. Every girl up until now always fell for his drop-dead looks.

Elsa merely stared back in resignation. "Fine. I'll do it. Hand me the textbook."

Across from the table, she held up the book at a distance just enough for him to see the pictures, but not the labels.

In the few minutes he had ever heard her talk the most, she would point to a part and ask him to name it. Nine times out of ten he would say the slang word and laugh over it.

Elsa clearly wasn't amused. "Saying things like 'clit,' 'cock' and 'pussy' aren't going to count, Jack. You need to say the proper terms to get full credit on the tests."

Jack fell over in his seat as he cackled. "How can you say those with a straight face? You really are something, Elsa."

Her face remained serious. "You're not in middle school anymore, Jack. Grow up. You suggested that we do this in the first place, so either make an effort to learn, or don't waste my time."

Her aversion to him both perplexed and intrigued him. He expected to feel hurt, but he was determined more than ever to get closer to her. Even in her anger she still looked quite attractive. But Jack would much rather be on her good side.

On her part, Elsa felt guilty for coming off as mean and hostile. How else could she keep him from suspecting she had the biggest crush on him? Especially when she was fully convinced she stood no chance of ever catching his attention.

After days of intense studying and help from Elsa, Jack got a much better grade on the third test. Mr. Bunnymund and his mother encouraged him to continue being tutored by Elsa, to ensure he would survive biology.

He showed off his grade to Elsa, who actually smiled back; his joy was too infectious to resist. "Good job, Jack. I'm happy for you."

'You're so beautiful when you smile.' Jack almost said that out loud, but kept his mouth shut to avoid fizzing out what little happiness he had seen from her.

Jack had been getting much better at learning when she quizzed him. In turn, Elsa found that she talked to him a little more each day. But it wasn't enough for Jack.

She started to put away her notebooks and end the tutoring session, then Jack mustered up the courage to say, "Elsa...I know you were pushed to do this, but thanks so much for taking time out of your day to help me. I don't think I can thank you enough. I'd do anything for you."

His sincerity took her by surprise. Elsa made to open her mouth, then she blushed furiously and fixed her gaze to the floor.

He tilted his head. "What is it? You want something? It's okay, Elsa. You can tell me."

"C-could I really...?"

Jack put up his hands and shrugged. "Sure."

Her lips moved as she muttered something.

Jack leaned in closer, straining to hear. "What's that?"

She said it a little louder, but still indiscernible.

"Say it again, Elsa. I can't hear you," he gently prompted.

"I want you to fuck me!"

Her outburst utterly shocked him. He simply stared, speechless.

Tears sprang to her eyes and she buried her face into her hands. "I'm sorry. I've liked you for the longest time, it just came out...I wasn't thinking...oh God, I'm so sorry."

Elsa wanted to crawl into a hole and never come out. What possessed her to divulge her secret, silly fantasy? Too late to take it back now. And she was never one to joke around or laugh it off. Now he was going to turn her down, and she'd never get over it.

'Elsa, the perfect girl, the kind who'd never fall for a bad boy like me...actually likes me?' He felt guilty for making her cry. He put up his hands to try calming her down. "Hey, hey...it's okay, don't cry..." He gave her a soft smile. "Well, guess what? I like you too."

Mixed emotions flitted across her pretty face. Confusion, joy, disbelief. "Really? You mean that? But why me...?"

"Why you?" Oh, the things he could possibly say to her. In his excitement to confess a million things he loved about Elsa all at once, in the end Jack just couldn't put it into words. "You're everything," he managed to say. "Smart, talented, beautiful and kind...you're perfect. You're too good for me. I didn't think I'd be the guy you want. Or deserve."

Elsa just stared at him in disbelief. Jack really did seem sincere. Sure, she was smart, hard-working and kept herself clean and looking decent. But she never considered herself beautiful. The most popular guy in school, attracted to her...for all her brains, she couldn't wrap her head around the idea. It seemed unreal. "I...I don't know what to say..."

"Say that again," Jack murmured in a low voice. "What you want from me."

"I...I want you to fuck me," Elsa shyly whispered.

A surge of arousing warmth engulfed his body as those words left her lips. The effect she had on him was intoxicating. She wasn't even trying to be seductive and coy, like so many girls that try and fail to snag him. Here she was, being honest and just being her pure, wonderful self.

Elsa looked away, wringing her pale, delicate hands. "I'm sorry," she said again. "I'm asking of you something totally ridiculous. How could I ask that when I have an aversion to touching people? I don't even hug or kiss my sister very often."

His heart went out to her, feeling a fondness more than lust. He really wanted to pull down that barrier she had been putting up for God knows how long. Jack wanted to make her happy, more than anything. He wanted to show her just how good it felt to be touched and loved.

Jack reassured her with an encouraging smile. "We'll start out slow, okay? We'll start with a touch."

With his right hand he reached out. Elsa didn't pull her own hand away. She sat stock still, letting Jack take her hand into his. His fingers intertwined with hers, pressing their palms together in a firm yet gentle squeeze.

"You're cool..." she murmured.

"You're not cold?" he asked.

Elsa managed a little smile. "I like the cold. It doesn't bother me."

And just when he thought he couldn't love her more. He wanted to kiss her right then and there. But not yet.

In one smooth move he squeezed his hand into a fist and pulled her in to close the distance between them. He enveloped her with a gentle embrace, one arm over her shoulder. He felt the firm softness of her chest, her heart beating with his beneath their thin shirts. Elsa felt like she could melt in his arms. Never in her life had she been this close to anyone before. Not since her parents, who had been dead for years. She pressed her cheek against the hollow of his neck.

"What's next?" she meekly asked. Without a word, he answered by tilting her chin up, leaning down to plant a tender kiss on her lips. Her eyes flew wide for a split second. Then they fluttered shut as she savored the touch of his cool lips against hers. She pulled away, only for Jack to capture her mouth again in a deeper kiss. He heard and felt her utter a soft moan as he slipped in his tongue past her parted lips. Their single deep kiss dissolved into many smaller ones, their lips meeting and parting but never quite breaking away. With one hand Elsa grasped the side of his head, feeling his white bristly hair under her fingers. The room was silent save for their rapid, needy breathing and the wet, intimate sounds of their cool lips and heated tongues. Finally Jack and Elsa broke away with flushed faces and hungry pants.

"Wow, not bad for a first kiss..." he breathed.

Elsa bit down on her swollen bottom lip. "That felt amazing."

He flashed her a roguish smirk. "It's just the tip of the iceberg."

Elsa shivered at the thought of what he would do to her next. It still felt like a dream. She fought to catch her breath, making Jack notice with appreciation how ample her chest was as she panted.

She blushed when she caught the intensity and direction of his hungry gaze.

His hands moved down to straddle her hips. "Got time to give me one more lesson?"

"I think you'll be the one giving _me_ the lesson." Elsa didn't think she could get any redder.

Jack shrugged. "Hey, maybe we'll both learn something." Much as it pained him, he pulled away from her to dim the lights of the room. He gathered Elsa into his arms again, lifting her effortlessly onto a table.

His low whisper tickled her ear. "I guess this is my reward for getting a good test grade."

Thankfully, with the remainder of the school year fast approaching summer, neither of them had much layers on. His hands flitted from her legs to tug at the hem of her shirt. Elsa looked startled, but only for a moment as she let him pull the shirt over her head. He leaned back, eyes wide and alight with admiration.

"Wow, even better than I imagined," he murmured.

Elsa flushed at the compliment, resisting the urge to cover up her body in shame. The black tabletop beneath them only made her pale skin look all the more whiter. White, like freshly fallen snow. He leaned in to trail light kisses down her neck, along her collarbone, across the dusting of freckles he could only notice from being this close to her. A sigh of content escaped her lips as she leaned back, submitting herself entirely to his careful attention and unrelenting adoration. Jack did not fail to overlook the sexy black bra she wore. She shivered as she felt his fingers at her back and unclipping her bra. As soon as he slipped it off Elsa pressed her bare chest against him, against the fabric of his shirt, eliciting tight-lipped moans from them both.

Jack then unbuttoned her jeans and pulled them down, revealing a pair of black lacy panties underneath. He whistled. "Damn, Elsa. I never thought you'd be one to wear this kind of thing."

She blushed. "It was Anna's idea. She completely redid my wardrobe. For better or worse, I'm not sure."

"Well, if she filled it with sexy stuff, I give you my one hundred percent approval." He couldn't stop marveling at how attractive she looked in her sensual undergarments. "I like it...I like it a lot. But it has to go."

He fingered at her underwear, and with one smooth move pulled it down her legs and tossed it away. Elsa's gaze shot down in embarrassment and alarm. Never in her life had she let anyone see her completely naked. She shrank under Jack's gaze, quickly drawing her legs together and folding her arms across her bare chest.

"I'm sorry-" she started to say.

A loving kiss to her lips cut her off. "No need to say sorry," Jack murmured. "You're absolutely gorgeous." He held her in his hands reverently, worshiping her body with his amorous gaze and touch.

He pressed his waist up against her sensitive core, eliciting a gasp from Elsa as she shut her eyes and felt the roughness of the denim and the hot, throbbing hardness underneath.

"Feel good?" he purred.

Her head jerked in a wordless, wanton nod.

"Then you're gonna love it when you'll have all of me inside you."

Elsa shuddered and moaned. She pressed her naked body against him, the couple heatedly grinding and passionately making out against the table. Jack decided he had enough of his clothes. He broke away to pull off his shirt, not caring where he tossed it as he shut his eyes and locked lips with her again. After another frenzied bout of kissing, Jack broke away once more as he fumbled to unzip his pants.

Elsa looked down and sucked in a shocked breath. She'd seen all the pictures, but she never knew Jack could be so..._big_.

Nervousness fluttered in her chest. But only for a moment. More than anything she wanted all of him between her legs, filling her and driving her to unimaginable rapture.

And _he_ wanted nothing more than to plunge straight into her wet, tight depths. But he decided he would have some fun with her first.

"Let's see if I'll get this right..." With two fingers, Jack prodded her entrance. Elsa gasped and spread her legs wider as he smoothed his fingers over her folds.

"The labia majora..." He was rewarded with a breathy "yes" from her. He went further in. "The labia minora..." Another "yes" from Elsa. He smirked as he pressed in towards the top. "The clitoris."

She spasmed from the bolt of pleasure as soon as he touched there. "Oh God, _yes_!" she cried.

"You know, I learned something interesting about the clitoris." He gently massaged that spot, sending more spasms through her body as she mewled and clutched at him. "It's derived from the same erectile tissue as the penis," he continued in a smooth low voice. "Further in the human embryonic stage, the differentiation of that common tissue is what separates male from female. That's why it feels so good when I touch you there." He met her eyes. "Am I right?"

"Y-you are. I'm impressed," Elsa managed to say.

He grinned at her. "I love it when I get extra credit right. But I left out one very important part..."

His fingers slid in past her entrance, making her tense and let out a high-pitched moan. To his delight she felt so wet and tight inside, ready just for him.

Elsa writhed underneath him, clearly in needy agony and pleading. Her voice was ragged and thick with desire. "I want you, Jack. All of you. I can't take it anymore."

He pretended to look doubtful. "You sure? We could stop-"

"No, don't."

The way she cut him off by grabbing his arms both surprised and thrilled him.

Jack chuckled. "You want me that badly, don't you, Elsa?"

"Yes, yes, _please_." Tears rimmed her eyes.

Jack wasn't going to make poor Elsa wait any longer. He didn't think he would last long either. He reverently parted her legs and pushed deep into her in one smooth thrust.

She threw her head back and let out a cry of mixed pain and ecstasy. Jack being the first man to take her was clearly, delightfully obvious.

"Are you okay, Elsa?" he asked with concern. "Are you hurt?"

"A little," she shakily admitted. "But I'll get used to it." Elsa tried to reassure him with a tiny smile. "You feel really good."

"Yeah, you too," Jack groaned. He gripped her thighs and moved in and out of her with slow strokes. "Damn, you're tight." he grunted through gritted teeth.

"I-is that bad...?"

Her innocence made him break into a wide grin and gaze at her fondly. "Not at all, Elsa." He rested his palm in her cheek. "Like I said, you're perfect."

Jack locked her into a heated kiss. He started to pick up pace as she moved her hips with his. His hips gyrated, the muscles on his chest and stomach straining as he rammed into her with swift, powerful thrusts. Her fingers dug into his skin. A shiver ran down his spine. She let out a breathy, high-pitched moan with each thrust, rising in volume as waves of pleasure overwhelmed her.

His cool breath tickled her ear. "Shhh...easy, girl. We don't want the whole school to hear you."

Elsa bit her lip, squeezed her eyes shut and buried her face against his neck as she fought to soften her moans into whimpers. It was all she could do not to scream. He went at her like an animal in heat. He was ruthless, relentless. Her thighs clamped tightly around his waist, pulling him in deeper and harder into her. He wanted time to stop, for this to last forever.

"Yes, yes, yes...oh, _fuck_..."

He just loved it when she said that. Something about the shy, homely good girl being naked under him and cussing turned him on. He peppered her with sweet, small kisses on her cheeks and down her jaw, to settle at her pale, smooth neck and leave tiny bites with each kiss.

He uttered sweet nothings against her skin, sweet words interlaced with his ragged pants. "Elsa, I love you...I love you so much...you're all mine, my lovely, wonderful Elsa..."

Sheer overwhelming pleasure soon dissolved his words into unintelligable moans as he felt his climax approaching.

"I...I love you too," Elsa replied breathlessly. Despite herself, she slipped out a cry as he pistoned in and out of her. "Make me hurt...make me feel good..."

Jack shut his eyes and saw stars as he exploded. He rode out the peak of his ecstasy, feeling his essence flood her insides. Jack's warning to keep quiet completely flew out the window, out of Elsa's mind, as she threw back her head and cried out in wordless ecstasy. She forgot to apologize, and Jack never said anything to reprove her. The sound of passionate, wet, almost violent slaps of their joined hips competed with the sound of their moans. After what seemed an eternity of spending every last drop on her, Jack slipped out and collapsed next to Elsa on the table.

She wanted to say something, but sheer pleasure and exhaustion robbed her ability to speak. Instead she let her head rest on his heaving chest. He ran his fingers through soft, flowing locks of her blonde hair. He looked down between her parted legs and looked back up with a sheepish grin.

"Sorry about the mess. I'll clean that up for you."

She tensed as his nose and lips brushed against her thigh. His tongue flicked out and glided along her skin, following the long, creamy trail that had trickled down her leg.

"You might want to have the table close for this one," he whispered.

He lapped and sucked at that sweet, still so tender spot between her legs. Elsa moaned and bucked her hips into his face, making him smirk as he gripped her hips and took his sweet time eating her out.

Elsa gasped and whimpered as she gripped the table. She only saw his head of white hair nestled firmly between her legs, but she certainly felt his mouth and tongue working diligently at her. Finally he pulled back and gave her a loving smile. He expected her to look disgusted; instead she gazed back at him with equal fondness.

"Wanna know a little secret?" he asked.

"What?" Her reply was so soft and breathless that he barely heard her.

"You're the first girl I've ever had sex with."

She gawked at him in surprise. "You're kidding!" she exclaimed. Then her face flushed again. "I-I was so sure...the way you...You mean to say you've never slept with anyone before me?"

His tousled hair and blue eyes made her heart skip. "I know all the girls drool over me, and I know people get the wrong idea that I sleep around. But I have eyes for you...only you, Elsa. I've seen for myself just how amazing you are when you open yourself up. And I meant more than just your legs."

She smiled at that. She appreciated the way he made her feel special, instead being just one of many girls to get maybe a wink or flirtatious words and nothing more than that. After what they've gone through together, there was no way the two of them could simply return to their former, separated lives.

"You enjoyed it, Elsa?" he asked.

She nodded without hesitation. "I did...I enjoyed it very much. Thank you, Jack." She leaned in to plant a chaste kiss on his forehead.

Gathering their composure and their clothes, Jack and Elsa helped each other clear the room of evidence of their passionate intimacy. She would never look at the classroom the same way again. Elsa consciously tugged the collar of her shirt higher up her neck. She was quite certain that Jack left a couple of visible marks on her skin. If Anna ever noticed, Elsa wouldn't hear the end of it.

The two of them started to leave the classroom together when Jack turned to her at the door. "If I ace the next test, will you go out with me?"

Elsa's hand flitted to her chest as she looked up at him with surprise. "Me? Be your girlfriend...?" She could only imagine what a whirlwind the two would kick up in school if they got together. Number one student in the class, going out with the number one ladies' man. She knew Jack would get a real kick out of it. And deep down, she knew she would, too. Elsa said nothing for a few seconds, then returned his hopeful gaze with a little smile. "I would be honored."

Jack thought his heart leapt into his throat. He masked his joy and shock with a suave wink. "Great. I'll study my ass off." Then he batted his hand against her hip in a teasing pat. "And while I'm at it, you keep wearing that sexy stuff underneath, for my eyes only."

She blushed. "Sure."

Jack had no excuse to flunk the rest of biology now.

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**Yeesh, writing smut is difficult. You can probably tell I'm quite the biology nerd. Anatomy and physiology is my favorite area of study. I like learning about human body parts and processes (so I can cut 'em up when I start practicing surgery wahahahaha). No really, I'd love to get into surgery and help out people that way.**

**Anyways...I hope you enjoyed the oneshot. I'd like to hear what you think; this was my first time writing smut (but definitely not my first time writing). I just kinda threw it out here to see what it's like. I'm a little embarrassed, actually. I probably won't write more smut anytime soon.**

**6/20/2014 update: Welp, looks like I did. There's now a sequel to "Learning Anatomy," also a oneshot. It's called "What Should I Say?" Check it out, if you want.**


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